The present studies are based on three species of the genus Costus viz., C. speciosus Sm., C. malortieanus H. Wendel and C. megalobractea K. Schum. C. spe-ciosus contains intraspecific chromosomal races namely diploid (2n=18), triploid (2n=27) and tetraploid (2n=36). This taxon has been studied in cytogeographic angle, and it is clear that the materials originating from different geographic regions of India have different ploidy levels. Intraspecific triploid hybrids (2n=27) were obtained by crossing natural tertaploid and diploid C. speciosus. The chromosome number recorded for the species C. megalobractea (2n=36) in the present studies is the first report on the taxon. The detailed karyotype analyses were made in all these taxa, while the meiotic analyses were carried out on the diploid and tetraploid cytotypes of C. speciosus. On the basis of the present cytological data, it can be concluded that polyploidy and structural changes of the chromosomes have played and important role in the evolution of the genus Costus.